1. Field of the Invention
This invention relates to a heating apparatus for heating articles such as an LSI package disposed on a carrier in an atmosphere of nitrogen.
2. Description of the Prior Art
FIG. 5 shows a conventional batch-type heating apparatus for heating articles such as an LSI package disposed on a carrier in an atmosphere of nitrogen. The heating apparatus has a heating chamber 72, the inside of which is heated by a heat source. The articles 60 are placed in the heating chamber 72, to be heated. When the articles 60 are taken in and out of the heating chamber 72, a door 73 of the chamber 72 is opened.
In replacing the heated articles 60 inside of heating chamber 72 with new articles 60 to be heated, it is necessary to take out the previous articles 60 from the heating chamber 72 before putting new ones in, so that workability is reduced. Moreover, although a plurality of articles 60 are heated in the heating chamber 72 at one time, it is difficult to keep the temperature distribution inside of the heating chamber 72 uniform, so that the articles 60 are heated to different degrees depending on the positions in the heating chamber 72 in which the individual articles 60 are placed. There is a possibility that some articles 60 are insufficiently heated while the other articles 60 are heated to the desired degree. Alternatively, if the articles 60 that have been placed in the positions of the chamber 72, heated are then heated to the desired degree, other articles 60 that have been placed in different positions of the chamber 72 must be overheated.
In addition to the heating apparatus mentioned above, a conventional continuous-type heating apparatus is also known, which is provided with a conveyor belt transmission system 81, as shown in FIG. 6, in which articles 60 to be heated are conveyed to a heating chamber 82 by the conveyor belt 81, and then passed through the inside of the heating chamber 82 while being heated. A belt 81a is wound around a pair of pulleys 81b, and when the conveyor belt transmission system 81 is operated, the belt 81a rotates around the pulleys 81b. The belt transmission system 81 vibrates during its rotation and the articles 60 on the belt 81a also vibrate while being conveyed, so that the heating apparatus is not suitable for heating articles 60, such as semiconductor devices or the like, because they must remain steady while being heated. Moreover, since the belt 81a rotates due to the frictional transmission between the belt 81a and the pulleys 81b, a residue of metal powder results from the friction between the belt 81a and the pulleys 81b. In the heating apparatus, a metal net with excellent heat stability is used as the belt 81a to resist the heating in the heating chamber 82 and the entrance and exit of the heating chamber 82 are normally opened, so that the metal powder resulting from the friction between the belt 81a and the pulleys 81b is scattered around the heating chamber 82.
Furthermore, in order to use the belt 81a made of a metal net or the like in the conveyor belt transmission system 81, a large driving unit becomes necessary.